How to remove slime from window air conditioner

Vertical A-coil air conditioners are popular models for home HVAC systems. Still, a common problem with these models is the accumulation of slime, which may appear like brown sludge in air conditioner drip trays. If you've got brown goo air conditioner problems, read on.

Cleaning Slime From Drip Trays

To start the cleaning, the experts at Bob Vila recommend that you disconnect the power supply to your air conditioner and put on chemical-safe gloves to prevent accidents and protect yourself. Much of the brown goo air conditioner is mold or fungus, so dispose of it properly. The drip tray is behind the coil access door, which may be screwed on, so you'll need a screwdriver handy. If you can't find that door, refer to your owner's manual diagram.

Spray an alkaline coil cleaner on the coils inside. Allow it to sit and drip into the tray below, which will begin to break up the jelly-like substance in air conditioner units; then, you can remove the drip tray to deep clean it. Use a putty knife or tool to scrape any hardened gunk off the drip tray. Use a hose, rinse any loose material in the tray and spray it generously with a corrosive cleaner. First, try using vinegar, but you may need something stronger.

Put a couple of condensate cleaner tablets in the drip tray and then put it back and reinstall the coil access door. Remember to restore power to your AC unit.

Window Air Conditioner Maintenance

It's critical to deep clean your window air conditioner at least once a year. Otherwise, accumulated dirt can impair its functioning or even break the machine. Worse yet, you don't want to breathe in the dust, mold and dirt.

Next, you should remove the unit from the window and take it outside. Remove the case and use your hose to spray it down. Use water pressure or cleaner to break up debris. You can also use a soft-bristle brush. Wipe down the unit's interior using your cleaner, rags and spray coil cleaner on any parts you can't reach. Be sure to clean the aluminum fins, interior base and fan.

Finally, you can use your hose to spray down the coils, tray and case. Before you reassemble the unit, allow everything to dry thoroughly.

Preventing Brown Sludge in Air Conditioners

You can do several things to prevent brown sludge from accumulating in your air conditioner in the first place, many of which are based on performing maintenance year-round. For example, the writers at Dengarden recommend using condensate cleaner tablets as a great preventative measure. These items slowly release chemicals that prevent mold and mildew from growing.

Similarly, you can put some vinegar on the bottom of the tray. A few tablespoons every month or two during the warmer months will usually prevent anything from growing inside the air conditioner, making the air in your home more safely breathable.

Of course, having your entire air conditioning unit regularly cleaned and properly serviced is critical to keeping the appliance running well. A dirty machine will naturally produce more harmful debris you don't want your family to breathe. For best results, have your HVAC system serviced annually and follow expert recommendations for maintenance.

Things You Will Need

• Aerosol alkaline coil cleaner

• Bleach or vinegar cleaner

• Condensate cleaner tablets

• Chemical-safe gloves

• Screwdriver

• Putty knife

• Hose

• Rags, paper towels and other cleaning materials

This story is part of Home Tips, CNET's collection of practical advice for getting the most out of your home, inside and out.

A window air conditioner can be a life-saver during the hottest months of the year, when staying home and staying cool are a top priority. But all of that heavy-duty use can really take a toll on your AC unit. To keep your window air conditioner in good working order, it's important to clean it regularly. 

By keeping your air conditioner clean, you'll prevent mold and mildew from growing inside and get more long-term value out of your appliance. Plus, a well-maintained window AC unit uses less energy than a dirty one. 

Cleaning a window air conditioner might seem daunting if you've never done it before. Fortunately, the process isn't as complicated as it may seem. With the following tips, you can keep your AC unit clean, functional and energy-efficient. (You can also check out our window AC buying guide. We've also got tips on how to fix a noisy air conditioner, and how to tell if it's time to replace your AC.) 

Read more: Lower Your Electric Bill This Summer With These Air Conditioning Tips

Gather your AC cleaning materials

You'll need a few items from around the house to give your air conditioner a thorough clean. Before you get started, grab the following materials: 

• Warm water
• Mild soap or detergent
• Reusable cloth
• Drip tray to place beneath your unit
• Spray bottle filled with 3% hydrogen peroxide
• Fin comb or soft-bristle brush
• Compressed air
• Screwdriver

1. Clean the filter

Cleaning the filter inside your window AC unit is the most critical thing you can do to keep it working smoothly. It's a good idea to wash the filter monthly, even if you don't clean the entire appliance. Here's how to do it.

First, make sure your air conditioner is unplugged, then take off the front panel and remove the filter. If it's covered in dust or hair, use a vacuum to clear away as much debris as you can. From there, wash your filter with warm, soapy water and set it out to dry. Wait until it's fully dry before putting it back into your window AC unit.

It's also a good idea to replace your air conditioner filter regularly. The exact frequency will depend on how much you use your AC and environmental factors, but you should aim to swap your filter out every six weeks to six months.

2. Wipe down the grill and exterior

While your filter is drying, wash the grill with warm water and mild detergent. Or if you don't want to wash it, you can instead use a damp reusable cloth to wipe it down -- just make sure to clean thoroughly in between the gaps where air comes out. Let it dry completely before reattaching it. 

Once you've cleaned the grill, wipe down the top and sides of the air conditioner. Take care to get inside of small spaces where it's easy for dirt and dust to collect. Wait until the grill and exterior are fully dry before running the unit.

3. Dust off the fins and coils

Now it's time to roll up your sleeves and get inside your AC unit. You don't need to dust the fins and coils every time you clean your air conditioner, but most manufacturers recommend doing it quarterly or semiannually.

First, take a fin comb or soft-bristle brush and gently comb the aluminum fins inside your AC. Take your time during this process because the fins bend easily and can be sharp. If you notice any bent fins, softly move them back into place.

Next, spray your can of condensed air inside the unit to dust off the coils. You should be as thorough as possible to remove any debris that could be preventing your appliance from working correctly.

4. Clean out the tray and drain

Finish the interior clean of your window AC unit by emptying the drip tray and clearing the drain. To remove debris or dirty water from your tray, grab a wet-dry vacuum (if you have one) or a damp cloth and pull out everything that's collected inside. Leave it to dry before reassembling.

Finally, check the drain to see if anything is blocking it. Use your cloth to wipe around the opening and make sure there's a clear pathway for water to exit your unit.

5. Reassemble and spray cleaner on your unit

After you've cleaned and dried everything, it's time to reassemble your window AC unit and give it a final spray to prevent mildew from growing. 

Grab your hydrogen peroxide spray bottle and apply the solution to the areas where air flows in and out. Wait for the peroxide to dry before using your appliance -- and you're done! Not only will you breathe in cleaner and colder air, but you'll extend the life of your air conditioner as well.

Final tips

In addition to cleaning it regularly, there are other steps you can take to keep your air conditioner in proper working order. For instance, remove it from your window and store it inside during the winter months or when you won't be using it for long periods of time.

If this seems like more work than you're willing to put in, you can always hire a professional to clean your window air conditioner for you. To find someone, ask your friends and family for referrals or check with reputable service providers in your area.

But whether you decide to bring in an expert or clean it yourself, just make sure to stick to a regular cleaning schedule. At a minimum, clean your filter monthly and spray your unit with hydrogen peroxide to fend off mildew.

More air conditioning advice

• How to Choose a Cool AC Window Unit
• Portable Air Conditioners: How to Buy the Right One and Stay Cool
• Window Air Conditioners vs. Portable Air Conditioners: Learn Their Key Differences
• 5 Tips to Lower Your Air Conditioning Bill While You're Away on Vacation

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